The most likely scenario is that neither Visa, Mastercard, ISIS, Square, nor anybody else will become the single, de-facto standard for mobile wallets and mobile payments. Theoretically, the consumer need for a universal and interoperable system is just too great for these companies to continue to fight it out while leaving money on the table.

My bet is that it will all work itself out. You can pay with Visa, Mastercard, and American Express using the same terminal. The same incentives to allow all forms of payment will work for both merchants and the payment system operators.